1. Field of the Invention
The invention relates in general to a capacitance measurement circuit and a method therefor, and more particularly to a capacitance measurement circuit for performing measurement in a differential manner, and a method therefor.
2. Description of the Related Art
Conventionally, a mechanical switch is usually adopted to implement a user control interface. A user needs to directly touch the conventional mechanical switch so that the conventional mechanical switch can perform an operation in response to a control instruction of the user. So, the conventional mechanical switch tends to be damaged in operation At present, a touch switch, such as a capacitive switch or the like, has been developed.
In order to enhance the convenience in use, a touch panel or a display touch panel with the display and touch functions, which have been developed, can accept the user's input or click. The touch panel or the display touch panel may be applied to various electronic devices, such as mobile telephones. Thus, the user can directly click frames on the touch panel or the display touch panel to perform operation, so that the more convenient and human-oriented operation mode may be provided. There are many kinds of touch panels or display touch panels, and a capacitive touch panel or a capacitive display touch panel is one of them.
When the user operates the capacitive touch panel, the capacitive display touch panel or the capacitive switch, the capacitance of the sensor capacitor therein is changed with the operation of the user. Thus, the operation of the user may be detected or sensed if the capacitance of the sensor capacitor and the variation thereof can be detected. However, it is a direction for the manufacturer to design a capacitance measurement circuit capable of effectively detecting the capacitance of the sensor capacitor and the variation thereof in order to enhance the performance of the capacitive touch panel, the capacitive display touch panel or the capacitive switch.
With regard to the current capacitance measurement circuit, however, the noise appearing in the input voltage source may be coupled into the capacitance measurement circuit so that the measurement result of the capacitance is affected.